1. Field of the Invention
This invention relates generally to patterned magnetic recording disks with annular data zones, and to disk drives with such disks.
2. Description of the Related Art
Magnetic recording hard disk drives with patterned magnetic recording media have been proposed to increase data density. In a patterned-media disk the magnetic recording layer on the disk is patterned into small isolated data islands arranged in concentric data tracks. In zoned or banded recording, the data tracks are grouped into annular zones, wherein the spacing of the data islands within each zone is fixed at one particular angular frequency for each zone. The angular frequencies for the zones are chosen so that the along-the-track spacing, or linear pitch, is approximately equal in all zones. This results in zones near the outside diameter (OD) of the disk having a higher data rate than zones near the inside diameter (ID).
However, due to tolerances in fabrication of the read head and write head, there is both an along-the track physical spacing and a cross-track physical spacing between the read head and the write head. Also, the slider on which the read head and write head are fabricated is moved across the disk surface in a non-radial arcuate path, which results in “skew” of the read head and write head relative to the data tracks. As a result of the physical spacings and head skew, there is typically an effective radial offset between the read head and the write head so that the read head and write head are generally not on the same track simultaneously. This effective radial offset causes problem when writing to data tracks near the boundaries of the data zones because the read and write heads may be in different zones, and each zone requires a different write frequency.
What is needed is a patterned-media disk with data zones and a disk drive that uses such disks that addresses the problem of writing to data tracks near zone boundaries.